The M occurrence is located along the ridge between Active and Howard creeks from elevations of 1545 to 1613 metres.

The area is underlain by argillite, limestone, mudstone, siltstone, shale and fine clastic sedimentary rocks of the Middle to Lower Ordovician Active Formation, which have been intruded by granodioritic rocks of the Cretaceous Anstey Pluton to the south.

Locally, sheared argillites and limestones contain a fault-related vein deposit. The fault zone strikes 150 degrees with a steep southwest dip. Within the sheared argillites a quartz gangue hosts bands of massive pyrite, pyrrhotite, sphalerite, galena, and minor chalcopyrite across widths of 1 to 2 metres and along a strike length of approximately 600 metres.

In 1974, drilling yielded 0.45 per cent lead and 2.0 per cent zinc over 11.7 metres in hole no. 1 (Assessment Report 5321).

In 1975, samples are reported have averaged 2.43 per cent zinc over 1.8 metres, with up to 15.4 grams per tonne silver, 1.38 per cent lead and 2.67 per cent zinc over 1.8 metres from the top cut and 14.7 grams per tonne silver, 0.29 per cent lead with 1.65 per cent zinc from the no. 3 trench (Property File - McLeod Copper Ltd. [1975-07-11]: Report on the M Claim Group).

In 1977, samples from surface trenches along the zone yielded from 2.06 to 3.12 per cent zinc (Assessment 6474).

The area has been explored since the early 1900s, with at least five trenches or prospect pits dating to this period. In 1974, two diamond drill holes, totalling 17.0 metres, were completed on the area as the M claims. In 1975, the area was examined by McLeod Copper Limited. In 1977 and 1978, programs of geological mapping and silt sampling were completed.